AHEAD
This project aimed at optimizing the powertrain of a serial hybrid electric bus for public transportation. First the optimal sizing of the powertrain components (sizes of combustion engine, supercapcitor, traction motor, etc) were found using optimal control theory. Then an optimal energy management was implemented on the vehicle. Using the standardized on-road test procedure it was shown that the serial hybrid electric bus consumes up to 27.5% less fuel than a comparable diesel bus. Running on a real busline for 3 weeks, the serial hybrid bus consumed 20-25% less than a comparable diesel bus.
The main final results of this project have been published in the external pageMTZ - Motorentechnische Zeitschrift Deutschlandcall_made in external pageGermancall_made as well as in external pageEnglishcall_made language.
This project was awarded the external pageWatt'dOr-Prizecall_made in the category "energy efficient mobility" in 2015.
The AHEAD project was a cooperation of external pageHESS AGcall_made (Bellach, Solothurn) and ETH Zürich, sponsored by external pageKTIcall_made and external pageBFEcall_made.
Currently, HESS AG and IDSC are collaborating with external pageVBZcall_made in the field of Trolley-Bus-Systems in the SwissTrolley+ Project.
Hardware of a serial hybrid powertrain
The bus is propelled by an electric traction motor (see figure below). Electric energy is delivered by an engine-generator set in the back of the vehicle. During downhill driving and braking maneuvers, the traction motors regenerate kinetic and potential energy, which is then stored in the electric double-layer capacitors (EDLCs) on the roof of the bus. This "recuperated" energy can be used for propulsion later on.
Components have to fit vehicle and mission
The components of the powertrain have to be adjusted to the primary use of the bus. If for example the route is a flat and straight road without many stops the components will be very different from the case where the bus is driven in a hilly city. This project develops methods and tools to find the optimal design for a vehicle's primary use.
Optimal energy management needed
During operation, the vehicle requires an energy management controller that decides upon the power split, i.e., how the traction power to be delivered is split up between the diesel generator set and the superacapacitors. A good energy management controller is crucial for good fuel economy. In this project, a fuel-optimal energy management controller was developed and implemented on the vehicle. Using the standardized on-road test procedure, it was shown that the serial hybrid electric bus together with the fuel-optimal energy management reduces consumption by 17.5-27.5% compared to a conventional diesel bus.
Information about future elevation profile allows saving energy
Nowadays, almost every city bus is equipped with a GPS receiver that allows to detect the position of the bus on the busline. Together with a map of the busline stored on-board, the system can provide specific data to the energy management system. This way, the supercaps can be discharged prior to long descend and recuperation energy that otherwise would have been lost can be used to recharge the supercapacitors. This way, the system is more robust to altitude variations on buslines.
Project goals
In public transportation, where buses run only on very few routes, the design of the vehicle can be specialized and optimized. This project seeks
- to find the fuel-optimal component sizes for a given vehicle on a given route;
to implement a fuel-optimal, predictive energy management strategy that takes into account the future elevation profile.
Practical outcomes
HESS benefits from
- reduced time and cost for development and design;
- the possibility to demonstrate and compare the performance of powertrain designs.
The costumer of a HESS bus benefits from
- 20-25% reduced CO2 emissions;
- 20-25% reduced fuel cost.
Scientific research topics
Hybrid electric vehicle design and optimization and predictive control of hybrid electric vehicles.
Final Results
Elbert P., Widmer M., Gisler H.-J., Onder C., "Systematic Optimization of a Serial Hybrid Electric Bus", 2016, MTZ - Motorentechnische Zeitschrift Deutschland, Vol. 77, No. 5, pp. 62-67, Read Article in external pageEnglishcall_made or external pageGermancall_made.
Peer Reviewed Journals
Elbert P., Widmer M., Gisler H.-J., Onder C., "Stochastic dynamic programming for the energy management of a serial hybrid electric bus," 2015, International Journal of Vehicle Design, Vol. 69 No. 1/2/3/4 pp. 88-112. external pageRead Articlecall_made
Elbert P., Nüesch T., Ritter A., Murgovski N., Guzzella L., "Engine On/Off Control for the Energy Management of a Hybrid Electric Bus via Convex Optimization," 2013 IEEE Transactions on Vehicular Technology, Vol 63, No. 8, pp. 3549-3559. external pageRead Articlecall_made
Elbert P., Ebbesen S., Guzzella L., "Implementation of Dynamic Programming for n-Dimensional Optimal Control Problems with Final State Constraints," 2012, IEEE Transactions on Control Systems Technology, Vol 21, No. 3, pp. 924-931. external pageRead Articlecall_made
Ebbesen S., Elbert P., Guzzella L., "Battery State-of-Health Perceptive Energy Management for Hybrid Electric Vehicles," 2012, IEEE Transactions on Vehicular Technology, Vol. 61, No. 7, pp. 2893-2900. external pageRead Articlecall_made
Ebbesen S., Elbert P., Guzzella L., "Engine Downsizing and Electric Hybridization Under Consideration of Cost and Drivability," 2012, Oil & Gas Science and Technology – Rev. IFP Energies nouvelles, Vol. 68, No. 1, pp. 109-116. external pageRead Articlecall_made
Nüesch T., Flankl M., Elbert P., Onder, C., Guzzella L., "Convex Optimization for the Energy Management of HEVs Considering Engine Start and Gearshift Costs," 2013, Energies, Vol. 7, No. 2, pp. 834-856. external pageRead Articlecall_made
Peer Reviewed Conferences
Elbert P., Onder C., Gisler H.-J., "Capacitors vs. Batteries in a Serial Hybrid Electric Bus," 2010, IFAC Symposium Advances in Automotive Control, AAC 2010, Munich, Germany.
Elbert P., Ebbesen S., Guzzella L., "Economic Viability of Battery Load-Leveling in Hybrid Electric Vehicles using Supercapacitors," 2011, Int. Scientific Conference on Hybrid Electric Vehicles, RHEVE 2011, Rueil-Malmaison, France
Ebbesen S., Elbert P., Guzzella L., "Engine Downsizing and Electric Hybridization Under Consideration of Cost and Drivability," 2011, Int. Scientific Conference on Hybrid Electric Vehicles, RHEVE 2011, Rueil-Malmaison, France
Gisler H.-J., Elbert P., "Capacitors vs. Batteries in a Serial Hybrid Electric Bus," 2012, 9th Symposium on Hybrid- and Electric Vehicles, IAV 2012, Braunschweig, Germany
We've won the external pageWatt d'Or prizecall_made in the category "energy efficient mobililty"!
2015
external pageWatt d'Orcall_made: external pagePhotoscall_made, Interviews: external pagePhilippcall_made, external pageChristophercall_made and external pageHans-Jörgcall_made, and the Energeia special issue.
2011
external pageEuropean Satellite Navigation Competitioncall_made: external pagePhotoscall_made, Brochure.
2010
Hans Eggenberger award: ETH-Life article.
09.01.2015
external pageEnergeia plus blogcall_made summarizes the Watt d'Or award ceremony.
08.01.2015
ETH Life, external pageSolothurner Zeitungcall_made and external pageSoaktuellcall_made report about HESS and IDSC winning the Watt d'Or award.
08.01.2015
external pageEnergeiacall_made explain in their special issue for external pageWatt d'Orcall_made how IDSC helps HESS to save energy. DownloadRead article. (PDF, 827 KB)vertical_align_bottom
01.03.2014
external pageEnergeiacall_made explain in their external pagelatest issuecall_made how IDSC helps HESS to save energy. DownloadRead article. (PDF, 644 KB)vertical_align_bottom
01.01.2014
The external pageOmnibusspiegelcall_made explains the concept of the HESS-Voith Hybrid bus. DownloadRead article. (PDF, 1.6 MB)vertical_align_bottom
27.11.2013
The external pageHeidenheimer Zeitungcall_made explain the concept of the HESS-Voith Hybrid bus. DownloadRead article. (PDF, 453 KB)vertical_align_bottom
21.10.2011
Congratulations! AHEAD was awarded the Downloadsecond prize (PDF, 417 KB)vertical_align_bottom and external pageRegional Winner of Switzerlandcall_made in the European Satellite Navigation Competition external pageESNC.call_made
21.06.2011
ETH GLOBE explain in their Downloadlatest issue (PDF, 8 MB)vertical_align_bottom how IDSC helps HESS to save energy. DownloadRead article. (PDF, 483 KB)vertical_align_bottom
21.01.2011
ETH Life reports on Philipp Elbert winning the Hans-Eggenberger Prize for his Masterthesis.
01.01.2011
Congratulations! Philipp Elbert's Masterthesis "Optimal Component Design for Serial Hybrid Electric Buses" was awarded the external pageHans Eggenberger Prizecall_made.
01.10.2007
external pageStadtbus.de Onlinemagazincall_made
This project is a cooperation with external pageHESS AGcall_made.
It is sponsored by external pageKTIcall_made.
08.01.2015
Watt d'Or 2015 Interviews:
external pagePhilipp Elbertcall_made
external pageChristopher Ondercall_made
external pageHans-Jörg Gislercall_made
09.09.2011
external pageAHEAD Project Impressionscall_made
14.04.2009
external pageVossloh-Kiepe explain their Hybrid Technology used in HESS's lighTram Hybridcall_made
29.05.2008
external pageA test drive in HESS's lighTram Hybridcall_made